Accumulator



Sept. 25, 1956 A FORD Eru.

ACCUIIULATOB Original Filed July 11, 1952 Nwn/ United states Patent one@ ACCUMULATOR Alfred Ford, Chicago, lll., and John W. Overbeke, Cleveland, Ohio, assigner: to Superior Pipe Speclaltlea Co., a corporation of Illinois originar No. 1,115,419, and August r6. 195s, senat N0. 29mm, my 11. rss2. Appliance an reime par 21. ross, senat No. sugars ll Claims. (CL 13b-3l) Matter enclosed In heavy brackets C] appeara ln the original patent but forms no part of thls re e cation; matter printed in Italia Indicates the additions made by reissue.

This invention relates to an accumulator for storing mechanical energy. Accumulator: of this type have a wide variety of applications which range from shock absorbers to storing potential energy to be discharged as kinetic energy. Thus as an example, accumulators may be used in connection with turning a heavy internal combustion engine for starting the same under adverse condi tions of cold or the like.

Accumulators must be constructed to withstand considerable pressure, while being mechanically simple and having a minimum amount of parts. This invention makes it possible to make an accumulator having valuableA features which render the same desirable from the point of view of manufacture and assembly and use.

Thus `an important feature in the construction to be described makes it possible for the movable element of the accumulator to move to the end of its discharge stroke without danger of mechanical shock. ln nsany such devices. a movable piston on reaching the end of its discharge stroke may strike the stationary part of the accumulator with sutlicient force to cause knocking and serious damage. A construction embodying the present invention endows the accumulator with piston-retarding means which is only operative at the end of its discharge stroke. The piston-retarding means comprises simple features of construction which in no way render the accumulator any more expensive or dimcult to manufacture or build.

The accumulator to which this invention pertains is of the type having an elongated outer casing within which is a sleeve. Within this sleeve is a floating piston. Suitable hydraulic pressure, such as from oil, for example, isv applied to one side of the piston. On the other side of th'e piston and within the casing structure as a whole is a quantity of compressible gas. As the piston moves under hydraulic pressure, the gas is compressed. l'he gas is inside and outside of the sleeve.

By suitable design of the thickness and dimensions of the sleeve as well as the outer casing, the capacity of the accumulator may be varied. Thus accumulator: of this type rnay have a length of from several inches up to as much as three feet or more. A feature of the present invention resides in the construction of the outer casing whereby centering of the sleeve within the outer casing is accomplished. This feature is of substantial importance in accumulators having substantial length.

As is well known, the operating characteristic of an accumulator is determined in a substantial degree by the compression ratio and by the variation of compression with piston movement. An important feature of the present invention makes it possible to provide accumulators having the same basic structure with different desired characteristics. Thus in the new accumulator, the construction is such that the outer casing and casing plug remain the same for all types. 'lhe plug construction Re. 24,223 Reissued Sept. 25, 19%

makes it possible to use dierent kinds of sleeves and pistons to obtain desired characteristics.

Thus with the same basic structure. accumulator; having various operating characteristics or having different combinations of outer casing and inner sleeve may be obtained.

An accumulator embodying the present invention has features which make it possible to use a compartively short piston. Thus. in conventional accumulators, a piston reaching the end of its stroke, irrespective whether it is charging or discharging, may be cocked and bind. lt has been customary to provide long pistons to avoid this. ln our new accumulator, it is possible to use a short piston and yet avoid binding at either end of the piston travel range.

Other features whose value will be apparent to and appreciated by those skilled in the art, will be obvious in connection with a description of the invention.

Referring to the drawings, an exemplary embodiment of the invention is shown, it being understood that modifications may be made without departing from the spirit of the invention.

Figure l is a longitudinal median section of an accumulator embodying the present invention, the piston being shown in its extreme discharged condition and the dotted lines showing the piston in a charged accumulator position;

Figure 2 is a section along line 2--2 of Figure l;

Figure 3 is a section along line 3-3 of Figure l.

The accumulator comprises generally cylindrical outer casing l0, having rounded bottom ll with filling end l1. (bsing 10 is of suitable material and, in practicel will be of drawn or forged steel having suitably heavy walls to withstand the pressure.

Filling end 12 is threaded internally to receive valve 14 and is externally threaded to receive cap 15. The filling channel may thus be conducted to suitable pipes for the introduction of air or gas under high pressure at an appropriate time. Under normal use, this end of the accumulator is sealed.

Outer easing 10 has open end 18. The interior of the outer casing is threaded at I9 at a region near end 18. Disposed within the outer casing is a sleeve assembly. generally indicated by numeral 2l. This sleeve assembly comprises sleeve member 23 having free end 2.4. ln order to center end 24 within outer easing 10. a number of indentations 26 are formed in the wall of the outer casing near the closed end of the easing to 'engage the outer surface of end 24 of the sleeve. As is evident in Figure 2, indentations 26 are disposed circularly along the wall of casing l0. As little as three indentations may be used. The indentation: are formed so that the free end of the sleeve is snugly retained and centered. Any inwardly (from the inside surface of outer casing l0) directed lingers or bosses may be used instead of indentations. `In the latter case, finishing of the bosses would be advisable for accurate centering.

Sleeve 23 is separate from, but permanently attached. to plug portion 28. Plug portion 18 is threaded to cooperate with threaded portion 19 of the outer easing. Plug portion 28 is provided with annular sealing recess 29 into which gasket 30 may be disposed. As is clear from Figure l, recess 29 and gasket 30 are disposed at an intermediate portion of plug 18 so that the gasket is forced inwardly within the end portion of outer casing l0. Over sleeve 23 is annular portion 32. This is welded or soldered at 31a to the plug portion and sleeve to provide a gas tight pressure seal.

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position having a substantial line contact and thus prevent cooking and binding of the piston.

7. The construction according to claim 6 wherein the linger projecting from the piston is tapered, the smallest part of the linger being at the tip.

8. The construction according to claim 7 wherein said piston has a pair of annular slots with piston sealing rings disposed therein and wherein said piston has a pressure equaiizing channel extending from the dome-shaped face of the piston to the surface of the piston between the two piston rings.

9. An accumulatorcomprising a cylinder having one end open and the other end closed, a plug cooperating with said open cylinder end [for closing the same] said plug having an axial bore therethrough for providing a passageway connecting the interior of the cylinder with the exterior, a floating piston within said cylinder, said piston being movable along the cylinder axis toward and away from the plug for energy discharge and energy charge respectively, said piston having a dome-shaped end provided with a finger projecting axially from the end for cooperation with the bore of the plug, said finger being adapted to enter the plug bore when the piston is near the end of its discharge travel, said piston having a pair of annular slots with piston sealing rings disposed therein and having a pressure equalizing channel extending from the dome-shaped face of the piston to the surface of the piston between the two piston rings, said plug having a concave surface facing the dome-shaped part of the piston, the dome-shaped part of the piston having a sharper curvature than the opposed plug concave 'surface so that the dome-shaped piston end meets the concave plug surface substantially along a circle lying in a plane substantially perpendicular to the axis of the cylinder whereby as the piston reaches its full end position corresponding to discharge, the piston will be guided toward a final resting position having a substantial line contact and thus prevent cocking and binding of the piston.

I0. An accumulator comprising an outer cylinder, means closing one end of said outer cylinder, means at the other end of the cylinder including a plug having a bore providing a restricted discharge opening for said other end of the outer cylinder, a sleeve coaxial with said outer cylinder and substantially axially coextensive therewith, a piston within said sleeve movable along the cylinder axis toward the plug for energy discharging, a finger projecting axially from the piston and extending toward the plug, said projecting finger being adapted to enter the bore, one of the opposed surfaces of bore and finger being tapered to lie in non-parallel relation to the other surface for providing an annular `fluid discharge region of increasing fluid flow resistance with final piston travel toward a fully discharged position.

II. In an accumulator, means enclosing an interior fluid pressure chamber and including a cylinder and a plug at one end of said cylinder, n piston disposed in said cylinder for axial movement therein toward the plug for energy discharging, a finger on said piston extending toward said plug, and said plug having a bore providing a discharge opening for said chamber and adapted to re ceive said finger therein, adjacent surfaces of said bore and said piston finger being non-parallel to define therebetween a fluid discharge region of increasing fluid flow resistance to final piston travel to a fully discharged position.

References Cited in the file of this patent or the original patent UNITED STATES PATENTS 1,949,640 Peters May 22, 1934 2,406,197 Christensen Aug. 20, i946 2,417,873 Huber Mar. 25, i947 2,421,076 Linton May 27, 1947 UNITED STATES PATENT QFFICE CERTmcATE 0F CORRECTION Reissue No. 24,223 September 25, 1956 Alfred Ford et al.

jIt is hereby certified that error appears .in the printed specification of the above numbered patent requiring correction and that the said Letters Patent 4should read as corrected below.

Column 2, line 3'?, for "conducted" read connectedcolumn 3, line 4, for "capacities of" read "capacities oI'-; line 75, for "balancng" read "balancingcolumn 4, line ,l, for "he plug" read --the plug".

Signed and sealed this 20th day of November 1956.

(SEAL) Atest:

KARL H' MINE r ROBERT c. WATSON Attesting Officer Comssioner Aruf Patents 

